The present invention relates to apparatus and a method for feeding and inverting a flexible tubular liner into the interior of a hollow tubular vessel, such as a previously existing underground sewer pipe.
Underground pipes are used as conduits for sewage or water supplies and may begin to leak after time as a result of ground movement, nearby construction, erosion, or other factors. It is well known to repair underground pipes by using fluid pressure to invert a flexible liner into the pipe, where the liners can be secured by chemically hardening resin with which the liner is impregnated before being installed. Previously, large, heavy and unwieldy containers have been used to retain and control fluid under pressure to urge the liner, originally in an inside-out condition, to extend along and through a length of underground pipe to be repaired by installation of the liner, and invert itself progressively in a required position. As used herein the term pipe is meant to include other elongate tubular structures that can be repaired by installation of such liners, as well as the sewer and water pipes specifically mentioned above.
One of the more successful pipe repair or rehabilitation processes which is currently used is described in Wood U.S. Pat. No. 4,064,211. Wood U.S. Pat. No. 4,385,885 discloses apparatus useful in installing a liner according to the process described in U.S. Pat. No. 4,064,211. Various sealing devices have been disclosed for use in connection with using fluid under pressure to extend and invert a liner into a conduit to be repaired, as shown, for example, in Alexander, Jr., U.S. Pats. Nos. 5,597,353 and 5,942,183, Long, Jr., U.S. Pat. No. 5,358,359, and Driver, et al., U.S. Pats. Nos. 5,154,936 and Re. 35,944.
Other apparatus for use in installing and inverting a liner, as disclosed in Long, Jr., U.S. Pats. Nos. 4,668,125 and 4,685,983, has been quite large, and has used a relatively tall column of water to provide the necessary fluid pressure within the liner being inverted. Such apparatus has been undesirably unwieldy and expensive, particularly for repair of large-diameter sewer pipes.
Waring et al. U.S. Pat. No. 6,390,795 discloses a smaller apparatus useful for installation of liners in medium sized pipes, but the apparatus still includes a rigid, heavy pressure containment vessel to which an end of a liner is attached, and through which the liner is fed.
What is desired, then, is to provide a conveniently small and inexpensive apparatus and an improved method useful to invert and install a flexible tubular liner quickly and efficiently into a pipe.